1. Field of the Invention
This invention is directed to UV (ultraviolet light) treatment of a clear coating to improve the acid etch resistance of the composition. In particular, this invention is directed to the UV treatment of a clear coating applied over a color coating of a motor vehicle such as an automobile or a truck to improve the acid etch resistance of the color coat.
2. Description of the Prior Art
Acid rain an other air pollutants have caused problems of water spotting and acid etching of finishes used on automobiles and trucks. The finish of choice presently being used on the exterior of automobiles and trucks is a clear coat/color coat finish in which a clear coating is applied over a color coat which is pigmented to provide protection to the color coat and improve the appearance of the overall finish such as gloss and distinctness of image. In an effort to solve these problems, U.S. Pat. No. 5,106,651 to Tyger et al issued Apr. 21, 1992 provides for UV treatment of clear coating of polymer containing active hydrogen such as acrylic polymers and an aminoplast crosslinking agent. However, there is no recognition or suggestion that other coating composition that did not contain an aminoplast resin would be affected by UV treatment in particular, silane containing coating which form particularly high quality clear coat and have excellent hardness and gloss.
There is a need for a process to treat silane containing clear coatings to form finishes that are resistant to acid etching and water spotting caused by acid rain.